This invention relates to analog signal processing, and more particularly to transceivers having signal strength measuring means.
This invention further relates to the transceiver and components thereof described and claimed in the following U.S. Patent Applications filed of even date with and assigned to the assignee of the present invention: U.S. Ser. No. 791,611 entitled "A Digitally Transmitting Transceiver" by Edward R. Caudel and William R. Wilson; U.S. Ser. No. 791,629 entitled "A Clarifying Radio Receiver" by Michael J. Cochran and Edward R. Caudel; U.S. Ser. No. 791,449 entitled "An Automatically Clarifying Radio Receiver" by Michael J. Cochran and Edward R. Caudel; U.S. Ser. No. 791,254 entitled "A Computer Controlled Radio System" by Michael J. Cochran and Edward R. Caudel; U.S Ser. No. 791,450 entitled "A Transceiver With Only One Reference Frequency" by Michael J. Cochran; U.S. Ser. No. 791,614 entitled "A Charge Transfer Device Radio System" by Michael J. Cochran; U.S. Ser. No. 791,253 entitled "A Transceiver Capable of Sensing A Clear Channel" by Jerry D. Merryman, Michael J. Cochran and Edward R. Caudel; U.S. Ser. No. 791,256 entitled "A Highly Selective Programmable Filter Module" by Michael J. Cochran and Edward R. Caudel; U.S. Ser. No. 791,616 entitled "A Duel Processor Transceiver" by Edward R. Caudel, William R. Wilson and Thomas E. Merrow; U.S. Ser. No. 791,264 entitled "An Electronic Phase Detector Circuit" by Michael J. Cochran. A transceiver has a transmit mode of operation and a receive mode. In a receive mode, the transceiver receives radiated electronic input signals comprised of a plurality of non-overlapping frequency bands, filters one of the bands from the plurality, frequency shifts the one band from radio frequencies to a lower frequency, and converts the filtered band to audible sounds. The input signals may be amplitude modulated (AM) or single sideband (SSB) signals, as an example. Antenna means receive the radiated input signals. Filtering devices are included in the transceiver to select one of the bands from the plurality. Mixing devices are included to frequency shift the selected band, and a demodulator device is included to demodulate the selected band. Similarly, in a transmit mode, a transceiver modulates electrical signals having audio frequencies, frequency shifts the modulated signals to radio frequencies of a selectable channel, and radiates the radio frequencies via an antenna.
When operating in the transmit mode, it is desirable that the operator receive some indication of whether his speech is being transmitted as intended; or whether a malfunction condition exists. To this end, transceivers have included devices for measuring the standing wave radio (SWR) on the transmitting antenna. The standing wave ratio is a measure of voltages on the antenna due to forward traveling waves in comparison to voltages due to reverse traveling waves. In general, the magnitude of the forward traveling wave is several orders of magnitude greater than the magnitude of the reverse traveling wave under normal operating conditions. Conversely, under abnormal conditions, the magnitude of the reverse traveling wave is equal to or greater than the magnitude of the forward traveling wave. Such an abnormal condition may be due to a physical damaged antenna, or an impedance mismatch between the output power amplifier and the antenna due to corrosion, as an example.
In the past, SWR measuring devices were manually activated. This is, the operator was required to depress one or more keys to enable the SWR measuring function. Also in the past, SWR measuring devices were comprised exclusively of analog circuitry. As a result, the operator was given an analog indication of the SWR; and the accuracy of the reading was limited by the accuracy of an electro-mechanical analog meter. Additionally, the operator was required to manually calibrate the meter. For example, the operator would first manually activate several keys such that the forward traveling wave gave a full-scale deflection. Reverse traveling waves were subsequently indicated relative to the full-scale deflection.
By comparison, the present invention includes an SWR measuring device which is automatically activated. Additionally, the disclosed invention is implemented almost entirely with digital circuitry. Further, the invention gives a digital readout of the SWR. Also, the operator is not required to manually calibrate the invention.
Accordingly, it is one objective of the invention to provide an improved radio transmitter.
Another object of the invention is to provide a radio transmitter having an SWR measuring device which is automatically activated.
Another object of the invention is to provide a transmitting radio system having a digital SWR display.
Still another object of the invention is to provide a transmitting radio system having an SWR measuring device which requires no manual calibration.